The present invention relates generally to medical devices, and more particularly to an ultrasonic medical device operating in a transverse mode for removal and remodeling of mammalian tissue in a controlled manner.
Demands for sculpting and improving body shape and its function using plastic surgery have become widespread and are frequently reasoned by the patient""s desire for such improvement. As a result, in addition to medically required surgical procedures for correcting congenital tissue malformations such as cleft palate, tissue remodeling is also performed for purely cosmetic reasons, e.g. to remove excessive fat tissue, correct hanging eye lids and to remove benign cysts, e.g. from the breast tissue. Generally, surgical methods involved in such procedures cause trauma, e.g., in the form of bruising and scarring, and patient discomfort. Furthermore, costs of postoperative treatment and recovery time can be substantial. Tissue removal using thermal methods, such as with laser devices, is often painful, and cause necrosis of the tissue area surrounding the surgical site that may require several weeks to heal. Therefore, surgical methods for tissue removal that are site specific in their mode of action and can be used with minimal trauma to tissue areas proximal to the surgical site are preferred, especially in the cosmetic procedures.
Medical devices utilizing ultrasonic energy to destroy tissue in the human body are known in the art. A major drawback of existing devices comprising an ultrasonic probe for tissue removal is that they are relatively slow in comparison procedures that involve surgical excision. This is mainly attributed to the fact that such ultrasonic devices rely on imparting ultrasonic energy to contacting tissue by undergoing a longitudinal vibration of the probe tip, wherein the probe tip is mechanically vibrated at an ultrasonic frequency a direction parallel to the probe longitudinal axis. This, in turn, produces a tissue destroying effect that is entirely localized at the probe tip, which substantially limits its ability to ablate large tissue areas in a short time.
One solution that has been proposed is to vibrate the tip of the probe in a transverse directionxe2x80x94i.e. perpendicular to the longitudinal axis of the probexe2x80x94in addition to vibrating the tip in the longitudinal direction. For example, U.S. Pat. No. 4,961,424 to Kubota et al. discloses an ultrasonic treatment device to destroy and emulsify concretions or tissue in a human body. The Kubota et al. device produces both a longitudinal and transverse motion at the tip of the probe. The Kubota et al. patent, however, still relies solely on the tip of the probe to act as a working surface. Therefore, it improves the efficiency of the tip, but still relies on the tip of the probe to perform all cutting actions.
Although Kubota et al. describe providing a transverse motion at the tip of the probe, a transverse motion along the length of the probe has generally been discouraged. For example, U.S. Pat. No. 4,474,180 to Angulo discloses an ultrasonic kidney stone disintegration instrument with a damping material applied to the wire probe to inhibit lateral vibrations of the wire in the region of the connection to the ultrasonic transducer.
Another proposed method of improving the speed of ultrasonic tissue remove is oscillating the tip of the probe in addition to longitudinally vibrating the tip of the probe. For example, U.S. Pat. No. 4,504,264 to Kelman discloses an ultrasonic treatment device which improves the speed of ultrasonic tissue removal. In the Kelman device, the tip of the probe is vibrated longitudinally and also oscillated, so that the cutting efficiency of the probe tip is improved. Again, however, only the tip of the probe performs a cutting action.
The present invention is directed to a method and an apparatus for treating tissue using ultrasonic energy. The present invention has particular application in removal of adipose tissue in an individual. The invention is further applicable in removal of tissue in eyelids during corrective surgery. The method of the present invention can also be used to remove benign cysts in the breast tissue. The apparatus of the present invention is designed to have a small cross-sectional profile, therefore allowing the apparatus to be used in a minimally invasive manner. As a result, the present invention is advantageous in that it can be used in cosmetic surgical applications in both traditional surgical sites and out patient treatment with minimal postoperative complications and minimal damage to areas other than the area of treatment. The present invention therefore provides distinct advantages over the prior art in the cosmetic surgical procedures, and therefore provides an improved method of cosmetic surgical procedures.